This study is the first to examine the relationship between nutrient enrichment and oviposition preference as measured by larval mosquito abundance using field-based mesocosms adjacent to wetlands in the Gulf Coastal Plain of Georgia. Agricultural wetlands in this region are known to have higher levels of nutrients and suspended sediments compared with forested wetlands, and previous studies have shown differences in mosquito communities in agricultural and forested wetlands. The purpose of this study was to determine whether nutrient enrichment contributes to the differences in mosquito oviposition preferences as reflected by larval mosquito presence and abundance in wetlands. We predicted that adding nutrients to mesocosms similar to concentrations in agricultural wetlands would favor responses of mosquito species often associated with nutrient-rich agricultural wetlands. Results indicated vegetation height, vegetation stem density, and phosphate levels were greater in fertilized mesocosms compared with nonfertilized mesocosms. The abundance of Aedes albopictus (Skuse) and Culex restuans Theobald was greater in mesocosms treated with fertilizer compared with nonfertilized mesocosms. Nutrient enrichment influenced oviposition and larval abundance of some mosquitoes of medical concern. This study provides evidence that can be used to predict the influence of nutrient enrichment on distribution and abundance of disease vectors and other nuisance mosquito species within an agricultural landscape.

Previous studies have used C and N isotope ratios to investigate the use of different food resources such as plant and animal detritus by container-breeding mosquitoes. This study is the first to report on the potential food resources assimilated by larval mosquitoes in agricultural and reference wetlands. Larval mosquitoes (Diptera: Culcidae) were sampled, along with their potential food resources, from agricultural and reference wetland habitats throughout a seasonal hydroperiod. IsoSource mixing model results indicated that food resources had greater δ 15 N isotope values in agricultural wetlands compared with cypress-gum swamps. In February, Aedes vexans (Meigen) and Culex territans Walker larvae fed primarily on lower quality food resources (coarse particulate organic matter and sediment) based on C:N. In contrast, higher quality food resources (fine particulate organic matter) were utilized by Anopheles spp. throughout the study and by Psorophora columbiae (Dyer and Knab) in May. This research contributes to a more comprehensive understanding of the food resources available and assimilated by larval mosquitoes in agricultural wetlands. Journal of Vector Ecology 39 (2): 288-297. 2014.